Control system



NOV. 10, 1931. p I B 1,831,069

CONTROL SYSTEM Filed Sept. 7, 1926 2 Sheets-Sheet 1 WITNESSE INVENTOR @rw/flg/i/hw Ray P H/gbee X6. BY

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ATTORNEY NOV. 10, 1931. R, HIGBEE 1,831,069

CONTROL SYSTEM Filed Sept. 7, 1926 2 Sheets-Sheet 2 F i? 70 y x w fjg /2 0 WITN s s- D C. ,4mpere5 gul. Mm/ 3 Ray I H/igee .GTAW .BY R

INVENTOR ATTORN ill Patented Nov. 10, 1931 FAY 1 3? E DG-EWQQD,

no ification or 39%, Serial 1%.. Hittite,

My invention relates to control systems and it has special relation to two-s eed con trol systems particularly adapted ror elevator or hoist applications.

One object or my invention is to provide a control system of the above-indicated char actor in which a motor Winding is adapted to utilize electric current of a given char-- acter, namely, alternating current, reactive device or the like being connected in circuit with the motor winding being governed to control the energization thereoi by applying current of a difierent character, namely, direct current, to reactive device,

More specifically stated, it is object my invention to provide a control system or the class under consideration in which a plural-legged core is provided wi Moth n alternating-current and direct-current coils, the direct-current energization so plied as to reduce the total volt-amperes or impedance drop of the entire reactive devic so that a motor may he smoothly accelerates or decelerated without the use of rheostats.

A further object of my invention is to provide a control system, the type lined and having either one or two speeds, in which the energization of one direct-current section of the reactive device is varied in accordance with the speed of the motor, preferably by means of a generator that is driven directly by the-motor,

Other objects or" my invention relate to the use of special relay devices for governing the relative operation oi the direct and alternating-current portions of my reactive de vices, as hereinatter described in detail,

Further objects of my invention will be come evident from the following detailed description, taken in conjunction. with the accompanying drawings, in which Fi ure 1 is a diagrammatic view of a twospeed system of control organized in accordance With the vention; I

Fig. 2 is a straight line diagram corresponding to the more complicated diagram of Fig. 1; and

Fig. 3 is a curve chart showing the resolt= principles of my present inant volt-ampere or impedance drop a1= acteristics of a variable reactive device iaed in accordance with my present inven tion,

My present invention is particularly adapted for controlling the induction type of motors, especially those having I stator windings, such as motors often em ployed for elevators hoist applications,

means of a variable reactive device canploying both direct and alternating-current windings, a variable voltage is applied to the primary Winding a motor in such n ner as to obtain smooth acceleration c 1 deceleration, C3

The reactance of iron-core reactor d pends upon the core flux density, by r as n of the variable permeability of the Thus, if the mean density oi the core controlled by combination of alt-era and direct-current err-citation, the eil ective reactance of'the apparatus may be controlled as desired in that, by the use of the r current Winding, any degree oi saturation .L the iron core Within the working range the reactor may be secured,

The approximate voltage range that r he obtained by means of reactors of the t;

question is indicated by he curves sho in lg. 3. The lowest limit of the v0 ge s consumed, that is, the difierence'hetween 18 line voltage and the voltage-applied to motor winding, would he, of course, fixed hy the impedance of the coils of the reactor without the iron core. It will be note th t, as the direct-current excitation of the reactor is increased, the volt-ampere capacity or ei drop due to. the reactor is decreased to approximately 9 volts.

It should be noted that the ratio between alternating-current and direct-current amperes, as indicated by the above figures,'1s not a power ratio. The direct current power that is required is that necessary to meet the copper loss and is, therefore, only of the order of one or two percent of the volt-ampere rating of the reactor.

Referring to Figs. 1 and 2 of the drawings, the system here shown comprises a polyphase supply circuit including conductors 10, 11 and 12; a two-speed induction motor 13, having a low-speed stator wind1ng'14 and a high-speed stator winding 15, both adapted to cooperate with a squirrel-cage rotor 16; a pair of reactive devices 17 and 18 that are associated with the low-speed stator WlIldll'lg 14; a second pair of reactive devices 19 and 20 that are associated with the high-speed stator winding 15; a generator or excit'er 21 that is driven by the squirrel-cage rotor 16 and is provided with directional field windings 22 and 23, respectively; a plurality of switches or 'contactors 24 to 29, inclusive, a plurality of controlling relays 30 to 33, inclusive, and a master switch or controller 34.

Whereas, for the sake of simplicity and clearness, I have shown my invention as applied to a two-phase, three-wire system, it should be understood that the invention may be readily applied to a three-phase system, by the addition of two reactive devices for cooperating with the third phase windings of the stator.

The lowspeed stator winding 14 comprises two independent phase windings 35 and 36 which have a common terminal conductor 37. Similarly, the high-speed stator winding 15 comprises two separate phase windings 38 and 39 having a common terminal conductor 40.

Each of the reactive devices 17 to 20, inclusive, comprises a three-legged core 43, upon the outer legs of which are wound alternating-current coils-41 and 42 and upon the intermediate leg of which a direct-current coil 44 is mounted. The alternating-current coils 41 and 42 are opposingly wound, but have the same number of turns, so that no alternatingeurrent flux will pass through the middle leg of the core or its associated direct-current coil. Any other suitablescheme for effecting this result may be employed, it being essential that the direct-current circuit be protected against high alternating-current voltages, inasmuch as the direct-current winding .44 necessarily employs a relatively large number of turns and very high voltages would otherwise be induced in that coil.

The master controller 34 comprises a suitable handle 45 for actuating a drum or disctype contact-carrying member 46, which cooperates with a plurality of stationary conlishes a circuit from supply conductor 11,

through switch member 56 of the reversing contactor, conductor 57, actuatingcoil 26 of switch 26, conductor 58, interlock or auxiliary contact member 59 of switch 28, conductors 60 and 61, switch member 62 of reversing switch 25, and thence to supply circuit eonductor 12.

The closure of switch 26 establishes a circuit from conductor 57, through contact member 63 of switch 26, conductor 64, the

parallel-connected alternating-current coils 41 and 42 of reactive device 17 and thence through low-speed phase winding 35 to the supply-circuit conductor 10.

A similar circuit is established from conductor 60, throughcontact member 65 of swltch 26, conductor 66, the parallel-connected alternating-current coils of reactive device 18, and thence through low-speed phase winding 36 to supply-circuit eonduetor 10.

Thelow-slpeedwindingsof the motor 13 are thus initial y energized to start acceleration of the motor, which drives the generator 21 and thus gradually increases the voltage thereof in accordance with the motor speed. 7 clrcuit is thus established from one termlnal of the generator 21, through field winding 22 thereof which corresponds to the then direction of rotation of the generator, eonductor 67, interlock 68 of reversin switch 25, conductors 69 and 70, interloc 7101. switch 26, conductor 72, contact member 73 of relay 31 in its lower or normalposition, and conductor 74, where the circuit divides, one branch including conductor 75 and the direct-current winding 44 of reactive device 17, while the other branch includes conductors 76 and the direct-current coil of the re-.

active device 18, the circuit being continued through conductors 77 and 78 to the opposite terminal of generator 21.

As the motor speed increases, the voltage of the generator and the current traversing the direct-current coils of the reactive device correspondingly increase to effect a gradual reduction of the effective voltamperes or impedance of the reactive devices 17 and 18 (as previously explained in connection with Fig. 3), which are connected in circuit with the respective low-speed phase windings of the motor 13.

A further circuit is completed. from condoctor 72, through the actuating coil 30 of relay 30, and conductor 83 to direct current return conductor 78. Consequently, the relay 30 is closed after a predetermined time interval, dependent upon the setting of the dash-pot of the relay, this time interval being adjusted to correspond to the motor reaching a speed substantially corresponding to the maximum speed that can be produced by the low-speed phase windings of the motor.

Upon the closure of relay 30, a circuit is established from conductor 57, through contact member'85 of relay 30, conductor 86, actuating coil 27 of switch 27, and thence through conductor 58 to supply-circuit conductor 12, as previously traced. 1

The closure of switch 27 establishes two new circuits, one extending from conductor 64., through conductor 87, contact member 88 of switch 27, and conductor 89 directly to the phase Winding 35. The second circuit entends from conductor 66, through conductor 90, contact member 91 of switch 27 and conductor 92 directly to the phase winding 36. In this way the alternating-current coils of the reactive devices 17 and 18 are short-circuited or excluded from circuit to permit the low-speed phase windings of the motor to bring the motor to the normal slow speed. To efi'ect further acceleration of motor 1.3, the master controller 34 may be actuated to a position in which the control finger 51 is energized, whereby a circuit is established through control finger 52, conductor 93 and the actuating coil 28 of switch 28 to conductor 60. The closure of switch 28 establishes a circuit from conductor 60, through conductor 94, contact member 95 of switch 28, conductor 96, the parallel-connected alternating-current coils of reactive device 19, and conductor 97 to high-speed phase winding 38 of the stator winding 15, and thence to supply circuit conductor 10. A. similar circuit is completed from conductor 57, through contact member 59 of switch28 in its upper position, conductor 100, the parallel-connected alternatingcurrent coils of reactive device 20, and conductor 101 to the other high-speed phase winding 39 oi the motor 13.

The motor thus accelerates in accordance with this replacement of phase windings 35 and 36 by windings 38 and 39; and, at this time, switches 26 and 27 are opened by reason of the exclusion of contact member 59 of switch 28 from the actuating circuits of their coils.

A direct-current circuit is concurrently established from one terminal of the generator 21, through field winding 22, as previously traced, to conductor 70, whence a circuit is continued through conductor 102, contact member 103 of switch 28, conductor 104,

where the circuit divides, one branch including conductor 105 and the direct-current coil of reactive device 19, and the other branch including conductor 106 and the direct-current coil of reactive device 20, a common circuit being continued through conductor 78 to the opposite terminal of the generator.

Another auxiliary circuit is established, upon the closure of switch 28, from conductor 104., through the actuating coil 33' of re lay 33, and thence to the direct-current return-circuit conductor 78. Relay 33 is adapted to close after a predetermined interval, corresponding to the reaching of approximately full speed by the motor 13, and after the increase in the direct-current traversing the reactive devices 19 and 20,

by reason of the increased acceleration of the motor, has reduced the efi'ective voltampere or impedance values of these reactive devices to a relatively low figure. The closure of relay 33 completes the circuit of the energizing coils 29 of switch 29, through the relay contact member 120, as will be noted,

The closure of switch 29 establishes two new circuits, one extending from conductor 96, through conductor 98, contact member 197 of the switch, and conductors 108 and 97 directly to high-speed phase winding 38, while the other circuit extends from conductor 100, through conductor 109, contact member 110 of a switch 29 and conductor 101 directly to the other high-speed phase winding 39.

ln this manner, the motor is brought to its full speed condition, as the alternating-current coils of the reactive devices 19 and 20 are thus excluded from circuit.

in order to decelerate the motors, the mas 29, corresponding to high-speed operation,

thus immediately open, but a circuit through reversing contactor 25 is maintained by means of a circuit extending from supply conductor 11, interlock 55 of reversing switch 24, actuating coil 25 of reversing switch 25, contact member 111 of that switch, conductor 112, contactmember 113 or": relay 32, and thence to supply-circuit conductor 10.

The actuating coil 32' of relay 32 is energized "from the generator armature, being connected in parallel to the actuating coil 31 ct relay 31 between conductors and 78, and thusmaintains the circuit just traced until the speed of the motor and generator is reduced to a point slightly greater than normal slow speed or the motor.

The opening of contactor 28 again closes interlock 59 through the previously-traced circuit to complete circuits through the lowspeed stator windings 35 and 36 and the alternating-current coils of reactive devices 17 and 18, as previously traced. The maximum voltage drop caused by these reactive devices is required only until the motor speed -is reduced to some intermediate value, usual- 1y corres onding to about one-half of the full spee value. The relay 31 is adjusted to drop at this value and to close the previouslytraced circuit through the direct-current coils of the reactive devices 17 and 18. By reason of the inherent time lag in a.device of large reactance, such as'the devices 17 and 18, the saturation of the cores will be effected gradually, so that the voltage drop across the alternating-current motor windings will likewise be reduced in a relatively gradual and smooth manner.

The closure of contactor 26, upon the opening of switch 28 (as previously described again'completes a circuit to relay 3O throug the auxiliary contact member 71 of the contactor. The dash-pot adjustment on relay 30 is such as to delay the closing of the actuating-coil circuit of contactor 27 until the voltage drop in the alternating-current coils of the devices 17 and 18 has become fully effective. In this manner the shortcircuiting of these coils is delayed to the proper point, and a very smooth regenerative braking torque is obtained. It will be seen that I have'thus provided a control system, especially adapted for twospeed alternating-current motors, in which a smoo h and gradual acceleration and deceleration may be effected without the use of r'heostats. The action of the control system is automatic and the characteristics of the system will be found to be particularly advantageous in the case of certain elevator and hoist applications.

I do not wish to be restricted to the specific circuit connections or arrangement of parts herein set forth, as various modifications thereof may be effected without de artin from the spirit and scope of my 1nvent1on. I desire, therefore, that only such limitations shall be imposed as are 1ndicated in the appended claims.

I claim as my invention:

1. A control system comprising a motor having a plurality of phase windings, a plurality of mechanically and magnetlcally independent reactive devices connected in circuit with the respective windings, a directcurrent generator driven by said motor, and means comprising a plurality of switches for selectively-connecting said generator to the respective reactive devices for governing the energization of said phase windings.

2. A control system comprising a motor having a plurality of phase winding groups for obtaining two pole numbers, a plurality of independent reactive devices severally having cores and a plurality of sets of coils wound thereon, the respective sets of one kind of coils being successively connected in circuit with said phase winding groups, a directcurrent generator driven by said motor, and means comprising a plurality of switches for selectively connecting said generator to the respective sets of the other kind of coils for governing the successive energization of said phase winding groups.

3. A control system comprising a motor having a plurality of sets of phase windings respectively corresponding to different 0 erating speeds of the motor, a plurality 0 reactive devices severally having cores and a plurality of opposingly wound coils thereon, the respective sets of coils being connected in circuit with said phase windings, an additional coil mounted on each core, a direct-current generator driven by said motor, and means comprising a plurality of switches for selectively connecting said generator to said additional coils for governing the energization of said phase windings.

4. A control system comprising a motor having a plurality of phase windings, a plurality of mechanically and magnetically independent reactive devices connected in circuit with the respective windings, a directcurrent generator driven by said motor, means comprising a plurality of switches for selectively connecting said generator to the respective reactive devices for governing the energization of said phase windings, and

. time-element means energized from said generator for selectively excluding the respective reactive devices from circuit.

5. A control system comprising a motor having a plurality of phase winding groups for obtaining two pole numbers, a plurality of reactive devices severally having cores and a plurality of sets of coils wound thereon, the respective sets of one kind of coils being successively connected in circuit with said phase Winding groups, a direct-current generator driven by said motor, means comprising a plurality of switches for selectively connecting said generator to the respective sets of the other-kind of coils for governing the successive energization of said phase winding groups, and time-element means energized from said generator for selectively excluding the respective reactivedevices from circuit.

6. A control system comprising a motor having a plurality of sets of phase windings respectively corresponding to difi'crent 0 erating speeds of the motor, a plurality 0 reactive devices severally having cores and a plurality of opposingly wound coils thereon, the respective sets of coils being connected in circuit with said phase windings, an additional coil mounted on each core, a direct-current generator driven by said motor, means comprising a plurality of switches for selectively connecting said generator to said additional coils for governing the energization of said phase windings, and time-element means energized from said generator for selectively excluding the respective reactive devices from circuit. 7

7. A control system comprising a plurality of phase windings of a motor, a plurality of mechanically and magnetically independent reactive devices connected in circuit with the respective windings, a source of direct current, a plurality of switches, and means for selectively governing said switches. to apply direct current from said source to the respective reactive devices, whereby the energization of said windings is successively obtained.

. 8. A control system comprising a plurality of phase winding groups of a motor for obtaining two pole numbers, a plurality of independent reactive dcvices severally having cores and a plurality of sets of coils wound thereon. the respective sets of one kind of coils being successively connected in circuit with said phase winding groups, a plurality of switches. a source of direct current, and means for selectively governing said switches to apply direct current from said source to the respective sets of the other kind of coils, whereby the energization of said winding groups is successively obtained.

9. A control system comprising a plurality of phase winding groups of a motor for obtaining two pole numbers, an alternatingcurrent circuit for energizing said windings to operate the motor, a plurality of independent reactive devices severally having cores and a plurality of opposingly wound coils mounted thereon, and the sets of such coils being successively connected in circuit, with said phase winding groups, an additional coil mounted on each core. a source of direct current. a plurality of switches, and means for selectively governing said switches to apply direct current from said source to the sets of said additional coils, whereby the energization of said winding groups is successively obtained.

10. A control system comprising a motor having a plurality of phase windings corresponding to different operating speeds thereof. an altern ating-current circuit for ener- 2121112 said wmdrngs to operate the motor. a plurality of reactive devices connected in circuit with the respective windings, a plurality of switches, a source of direct current. and means for selectively governing said switches to apply direct current from said source to the corresponding reactive devices, whereby the energization of said windings is successively obtained.

11. A control system comprising a plurality of phase windings of a motor. a plurality of mechanically and magnetically independent reactive devices severally having cores and a plurality of sets of coils wound thereon,

one of the respective sets of coils being connected in circuit with said phase windings, a plurality of switches, a source of direct current, means. for selectively governing said switches to apply direct current from said source to another set of coils, whereby the energization of said windings is successively obtained, and means responsive to the speed of said motor for successively governing the inclusion or exclusion of certain coils of the respective reactive devices.

. 12. A control system comprising a motor having a plurality of phase winding groups for obtaining two pole numbers, an alternating-current circuit for energizing said wind ings to operate the motor, a plurality of reactive devices severally having cores and a plurality of sets of coils wound thereon, the respective sets of one kind of coils being successively connected in circuit with said phase winding groups, a plurality of switches, a source of direct current. means for selective- 1y governing said switches to apply direct current from said source to the respective sets of the other kind of coils, whereby the energization of said winding group is successively obtained, a generator driven b said motor, and means responsive to the v0 tage of said generator for successively governing the RAY P. HIGBEE. 

